The present invention relates to a high-speed electrical data transmission system. The invention relates more particularly, although not exclusively, to a cost-effective system for electrically transmitting data in local area computer networks and other communications networks.
Modern methods of transmitting data signals by cable include fibre-optic communication, Low Voltage Differential Signalling (LVDS) and single ended signalling.
Fibre-optic systems are presently used to achieve high-speed data transmission over long distances. For example, high-speed broadband Internet and pay-TV networks and telephone networks have employed this technology. However, due to high costs of fibre-optic transceivers, the difficulty of splicing fibre-optic cables and the inability to convey electrical power in addition to data signals, fibre-optic networks have not extended the whole way to each end-connection point such as home or office modems, telephones or pay-TV receivers. Rather, the fibre-optic network extends to a fibre-optic transceiver “node” or “hub” employing optical-to-electrical (and vice versa) signal conversion and from which an electrical network extends to the various points of connection. For example, the signal from a fibre-optic transceiver having been converted into electrical voltage-fluctuation signals is connected by electrical cables to appliances such as home computers, telephones and pay-TV receivers in private premises and offices for example. For this reason, data signal from the fibre-optic transmission line to individual premises is by converting the optical signal into an electrical signal in a shared fibre-optic transceiver. The electrical signal is conveyed by LVDS transmission lines to electrical appliances such as personal computers (say in a local area network), telephones, cable televisions etc.
Although there have heretofore been disadvantages in the implementation of electrical cables from the transceiver to the various endpoints—particularly associated with cable length restrictions, there are advantages in adopting electrical cabling to transfer data and these include lower cable cost, ease of splicing electrical cables and the presence of existing in situ cable networks. Although LVDS transmission has replaced single-ended signalling transmission as it provides a higher data transfer rate and better resistance to electromagnetic interference, LVDS systems remain susceptible to electromagnetic interference and signal degradation over extended cable lengths.